1. Field of the Invention
The present invention relates to a transmission with a reverse for a vehicle wherein a chain for reversing is provided in a transmission chamber.
2. Description of Background Art
A structure of a transmission with a reverse for a vehicle wherein a driving sprocket wheel is provided on a main shaft and a driven sprocket wheel is provided on a countershaft while a chain for reversing is wrapped around and extends between the sprocket wheels is known. See, for example, Japanese Utility Model Publication No. Hei 2-027712. With such a structure as just described, reverse traveling can be carried out without setting an idler gear on an idler shaft for reversing.
Since reverse traveling is carried out such that a vehicle begins to move from a stopping state, high torque is required with respect to rotational input power from an internal combustion engine, and a high reduction gear ratio is required.
In the structure disclosed in Japanese Utility Model Publication No. Hei 2-027712, in order to obtain a high reduction gear ratio for reversing, it is necessary to use a greater size difference between the driving sprocket wheel and the driven sprocket wheel. Therefore, also it is necessary to use a long distance between the main shaft and the countershaft. Thus, it is possible that the transmission chamber will increase in size.
Further, if the driving sprocket wheel is increased in size and the distance between the shafts is increased, then the chain is increased in length as well and the deflection region of the chain increases. As a result, the size of the transmission chamber is likely to be increased.